In industrial automation field, the use of robotic arms for handling objects is known. At the respective end, the robotic arms are provided with clamping grippers with two or more jaws. In particular, the grippers are provided with a body housing the jaws, or clamps, and the corresponding activating device. The jaws are movable between a first not-operating position or releasing position, where they don't apply any pressure on the piece to be manipulated and an operating position, or clamping position, where they apply a pressure on the piece to be manipulated adequate to provide the workpiece not becoming accidentally free during its movement. The device for activating the jaws can be of an electric, pneumatic, oleo-pneumatic, etc., type.
Depending on the number of the jaws and their movement, they can be grippers having two jaws, which can be parallel, radial or angular, grippers having three jaws, etc.
A kind of grippers has the clamping position corresponding to the jaws being proximal to the gripper longitudinal axis, for the external clamping of pieces that are inserted between the jaws themselves; the releasing position corresponds to the jaws distal from the gripper longitudinal axis.
In another kind of grippers, the clamping position corresponds to the jaws distal from the gripper longitudinal axis, for the inner clamping of pieces surrounding the jaws themselves; the releasing position corresponds to the jaws proximal to the gripper longitudinal axis.
Examples of grippers for industrial automation are provided in Italian Applications BS2012A000095, which describes a gripper with three jaws, and BS2012A000162, which describes a gripper with two parallel jaws, filed by the Applicant.
The Applicant found the need of using grippers also in the so-called clean-rooms, i.e. those environments with controlled atmosphere in which polluting microparticles must be removed, which otherwise would remain suspended in the air. The clean-rooms are mostly used to realize chemical and pharmaceutical laboratories.
In particular, the manufacturers of clean-rooms must adopt solutions to avoid instrumentations, objects and persons inside the room from polluting the air. The classification of clean-rooms is based on the count of microparticles having a diameter greater or equal to 0.5 μm in a defined volume of air (for example a cubic meter, in Europe). The count is made by means of a particle counter placed in the room. Fewer particles are counted, cleaner the clean-room is and better its quality class is.
In ISO regulations, the quality class is assigned according to a ranking from ISO-1 to ISO-9, where ISO-1 is the best performance and ISO-9 the worst.
In GMP European regulations, used in pharmaceutical field and considered as ones of the most restrictive, the quality class of clean-rooms is assigned by A, B, C and D letters, where A is the best performance and D the worst. For example, when a clean-room of A quality is used, the maximum number of particles admitted in the clean-room having a diameter greater or equal to 0.5 μm is 3520, and the maximum number of particles admitted in the clean-room having a diameter greater or equal to 5 μm is 20.
In view of what above, in clean-rooms the robotic arms are sealed with films or closed in rigid covers to avoid particles contained in the same arms from spreading in the air, for example originating from the wear of their components.